ProPublica: Since 1999, various studies have attempted to estimate deaths resulting from medical mistakes in hospitals, and each time the number seems to rise significantly.

In 2010, the Office of Inspector General for Health and Human Services said that bad hospital care contributed to the deaths of 180,000 patients in Medicare alone in a given year.

Now comes a study in the current issue of the Journal of Patient Safety that says the numbers may be much higher — between 210,000 and 440,000 patients each year who go to the hospital for care suffer some type of preventable harm that contributes to their death, the study says.